import java.util.Scanner;

public class Text {
    public static void main(String[] args) {
        //定义一个数组
        long[] arr = new long[81];
        arr[0] = 1;
        arr[1] = 1;
        for (int i = 2; i < 81; i++) {
            arr[i] = arr[i - 1] + arr[i - 2];
        }
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {

            int from = scanner.nextInt();
            int to = scanner.nextInt();
            long sum = 0;  //求总的和
            for (int i = from - 1; i < to; i++) {
                sum = sum + arr[i];
            }
            System.out.println(sum);
        }
    }
}
